1. Field of the Invention
This invention relates to lightweight, panels useful in building construction, particularly to such panels of a fire-resistant nature which are useful in constructing walls, partitions and ceilings, to methods of producing the panels and construction methods using the panels.
2. Description of the Prior Art
Over the years, many attempts have been made to create lightweight rigid panels for use in constructing permanent or demountable partitions or walls in homes and commercial buildings. With modern highrise construction, it has become even more necessary than ever before to use panels of a type which exhibit good fire-resistance so that they will pass the requisite fire tests and will withstand the conditions to which they are subjected during intense fires in such buildings. Gypsum material has long been utilized in the formation of panels for resisting fire. Gypsum is today typically used in the form of drywall made of gypsum wallboard panels fastened to a supporting skeletal structure or framework formed of wood or metal members. The gypsum wallboard generally comprises a core of gypsum having on its outer surface a layer of relatively heavy kraft paper. In a fire, the paper may support combustion for a limited period of time, but the gypsum core resists the fire while releasing its water hydration and therefore has a fairly predictable burn-through time during which it prevents the passage of fire.
Attempts have been made to create composite panels having a core of fire resistant material with a very thin layer of gypsum on each surface thereof. One such composite panel is described in Roberts U.S. Pat. No. 3,908,062 issued Sep. 23, 1975. That composite panel includes a rigid core of bonded mineral fiber material with a very thin layer of gypsum material on each surface thereof. The gypsum layer is preferably no more than about 1/8 inch (3 mm) thick and the complete composite board is typically of the thickness of a usual gypsum drywall panel.
Various other types of composite or sandwich constructions have been attempted in building construction and, for instance, Harvey et al U.S. Pat. No. 4,562,109 issued Dec. 31, 1985 describes a crack resistant coating for masonry structures comprising a trowelable mixture of a resin binder and glass beads. The glass beads used for this purpose had an average diameter of about 4 mm. A convention coating layer was applied on top of the crack absorbing layer containing the glass beads.
U.S. Pat. No. 2,806,509, issued Sep. 17, 1957, describes the fabrication of laminated sandwich panels in which hollow beads coated with a heat-tackifiable resin and a powdered metal is placed between outer skins and is then heated and compressed to compact the beads and gel the resin. Panels produced in this manner had a density of about 25 to 75 pounds per cubic foot.
It is the object of the present invention to develop a construction system using lightweight panels of substantial thickness which would be capable of comprising a complete wall or partition structure such as to eliminate any supporting skeletal structure or framework formed of wood or metal members. In other words, it would be capable of forming a complete wall or partition.